Acoustic feedback is a phenomenon that sound from a speaker is fed back to a microphone via a feedback path and is picked up by the microphone. The existence of the acoustic feedback adversely affects the sound field frequency response characteristic, and serious acoustic feedback may cause a shrill squeal, which seriously deteriorates the sound quality.
In order to suppress acoustic feedback, the following technical solution is adopted in the conventional technology. As disclosed in APPARATUS AND METHOD FOR DETECTING ACOUSTIC FEEDBACK, it is provided an apparatus which includes: a first level detecting section configured to detect a signal level of sound signals obtained from a position in a sound-signal system in which a microphone and speaker are connected; a first extracting section configured to extract, from the sound signals of which the signal level is detected, signals in a band having a bandwidth predetermined for each of at least one predetermined center frequency; a second level detecting section configured to detect a signal level of the signals in each band, the signals being extracted by the first extracting section; and a determining section configured to determine whether or not acoustic feedback is occurring, on the basis of a threshold determined according to the signal level detected by the first level detecting section and a waveform of each signal level detected by the second level detecting section.
In the above conventional technical solution, the first extracting section is implemented by multiple band-pass filters, which cannot cover the full frequency band due to the limitation in the center frequency and the bandwidth of the band-pass filter, thus the problem of missing of detection may occur. In addition, whether acoustic feedback occurs is determined by judging whether the waveform of the signal level is a sinusoidal periodic waveform, which may cause the problem of false detection.